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      Basal and GnRH-Induced Release and Synthesis of LH and FSH from Incubated Pituitary Glands throughout the 4-Day Estrous Cycle of the Rat

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          Abstract

          A comparative study of the patterns of LH and FSH released and synthesized during the normal estrous cycle of the rat was performed in vitro. Groups of female rats were killed at 09.00 h and 15.00 h throughout the 4-day estrous cycle and the adenohypophysis incubated for 4 h. Pituitary extracts and media were assayed for LH and FSH by radioimmunoassay. Both hormones exhibited maximum concentrations in tissue and medium on proestrus afternoon. The increased release of LH occurred during the day of proestrus, while that of FSH lasted from the afternoon of proestrus to the morning of estrus. Synthesis of LH exhibited a marked rising phase from the afternoon of diestrus-2 through the morning of estrus. When release and synthesis of LH and FSH were expressed as percentages of hormone concentration at the beginning of the incubation period, the percentages of FSH were greater than those of LH at all stages of the cycle. Addition of synthetic gonadotrophin-releasing hormone (GnRH) to the incubation medium was followed by a dose-dependent increase in release and synthesis of both LH and FSH. Pituitary responsiveness to GnRH reached a peak on the afternoon of proestrus and fell to a minimum during diestrus. Whereas maximum LH responsiveness correlated with the proestrus discharge of the hormone, that of FSH ceased before the basal release of the hormone, which terminates on estrus. The possible role of sex steroid hormones in regulating in vitro secretion of gonadotrophins and pituitary sensitivity to exogenous GnRH is discussed.

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          Author and article information

          Journal
          HRE
          Horm Res Paediatr
          10.1159/issn.1663-2818
          Hormone Research in Paediatrics
          S. Karger AG
          1663-2818
          1663-2826
          1981
          1981
          25 November 2008
          : 15
          : 2
          : 109-121
          Affiliations
          Instituto de Investigación Médica Mercedes y Martin Ferreyra, Córdoba, Argentina
          Article
          179440 Horm Res 1981;15:109–121
          10.1159/000179440
          6799380
          083f3786-9b3f-4d3f-87f3-9d2dc6a068ea
          © 1981 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          History
          : 06 March 1981
          : 03 August 1981
          Page count
          Pages: 13
          Categories
          Original Paper

          Endocrinology & Diabetes,Neurology,Nutrition & Dietetics,Sexual medicine,Internal medicine,Pharmacology & Pharmaceutical medicine
          Incubated pituitary glands,In vitro rat estrous cycle,Steroid hormones,Gonadotrophin-releasing hormone (GnRH),Follicle-stimulating hormone (FSH),Luteinizing hormone (LH)

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